Developing an Experimental Model for Effects of Heating Cycles and Temperature on Penetration, Softening Point and Penetration Index of Bitumen

Variation of bitumen useful properties after continuous heat and cold cycles is a weak point of this substance. The temperature of these heating cycles is effective on loss of properties too. Due to problems while transport، hauling and conserving bitumen from production to asphalt plant، the effect of heating cycles and bitumen heating temperature on properties such as penetration degree، softening point and penetration index should be considered. In this paper the mentioned effects were surveyed by performing penetration and softening point test on bitumen samples heated in various cycles and heating durations. The results showed bitumen properties loss intensely after heating cycles and went out of range which should be considered in designs. Finally six models to predict penetration، softening point and penetration index of 67/70 and 85/100 bitumen after heating cycles and in various heating durations were developed.